Halogenated hydrocarbon compounds include the families of compounds: bromo-, fluoro- and/or chloro-ethers, fluorinated alkyl ethers, chlorofluorocarbons and chlorofluoro ethers and their derivatives. These families of compounds are typically used as solvents, refrigerants, anesthetics, aerosol propellants, blowing agents and the like. Many of these compounds are widely used and are routinely discharged into the atmosphere. Particularly in the case of medical anesthetic gases, if these compounds could be recovered, retrieved and purified to medical standards there would be a considerable cost saving and reduction in environmental pollution. In view of the possible negative effects of halogenated hydrocarbons that are released into the atmosphere, attempts have already been made to recover such gases.
In view of the rising costs of the inhalation anesthetics and the environmental effects (e.g. toxic greenhouse and ozone depletion) of the drugs, attempts are being made to recover the inhalation anesthetics before the anesthetics are discharged into the atmosphere. A system can be provided for recovering inhalation anesthetics from gas streams exiting anesthetic gas machines (which may include patient exhalent following administration to a patient) by capturing scavenged gas containing the anesthetic rich gas stream, removing water vapor and then extracting the anesthetic using either a cryogenic process in which the vapors of the anesthetics are condensed to liquid phase, or an adsorbent material which is processed later to remove the anesthetics. The collected liquid anesthetics can then be reintroduced directly into an anesthetic gas machine. Such approach has little if any facility to control bacterial contamination and potentially recycles harmful microorganisms to another patient or the anesthetic gas machine in general. Additionally, there is no assurance that the condensed drugs are separated into individual components and that each recycled drug meets the appropriate medical standards and regulations.
In another approach for recovering inhalation anesthetics, an adsorbent material in an appropriate container is used to adsorb the inhalation anesthetics from the gas stream exiting the anesthetic gas machine. When the adsorbent material is saturated, the container is removed and placed in a regeneration system. A purging gas, such as steam, is used to remove the anesthetics from the adsorbent material. The purged gas is then collected, water is removed therefrom, and the anesthetics are condensed and subjected to fractionation to separate out the individual anesthetics. Such an approach can be difficult as steam, having an elevated temperature, can cause catalytic reactions with the adsorbent and adsorbate leading to a product breakdown and pure yields of the recovered anesthetics. Furthermore, such an approach can be difficult because a number of different inhalation anesthetics may be used in one operating room and each inhalation anesthetic may require different adsorbents and differing desorption requirements. Further, methods of separating a number of different inhalation anesthetics can be very complex due to differing chemistries and the potential for impurities, including by-products, in the combined materials.
Examples of anesthetics which can be captured are sold under the trade-marks ETHRANE and FORANE, and are disclosed in U.S. Pat. Nos. 3,469,011; 3,527,813; 3,535,388; and 3,535,425. The respective chemical formulae for these anesthetics are: 1,1,2-trifluoro-2-chloroethyl difluoromethyl ether and 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether. These chemicals are also commonly known as “enflurane” and “isoflurane”, respectively.
Other anesthetics of particular importance are sold under the trade-marks SUPRANE and ULTANE, and are disclosed in U.S. Pat. Nos. 3,897,502; 4,762,856; and 3,683,092. The respective chemical formulae for these anesthetics are: 2,2,2-trifluoro-1-fluoroethyl-difluoromethyl ether and 2,2,2-trifluoro-1-[trifluoromethyl]ethyl fluoromethyl ether. These chemicals are commonly known as “desflurane” and “sevoflurane”, respectively. They are highly volatile organic compounds, produced in a liquid form and then evaporated and mixed with other carrier medical gases, such as nitrous oxide, oxygen and/or medical air in the anesthetic gas machine before administered to a patient to be used as an inhalation anesthetic. The gas stream exiting the anesthetic gas machine is rich with inhalation anesthetics and contains entrained CO2 and moisture and possibly some by-products that potentially result from the anesthetic gas mix recirculation stream passing over soda lime absorbent in the patient breathing circuit.
While there may be methods and systems for adsorbing some of these anesthetics individually or for purifying some of these chemicals individually to a level for medical use, effective methods and systems of selective recovering anesthetics or a mixture of anesthetics from a gas stream, for separating the anesthetics, if necessary, and for purifying the anesthetics would be economically advantageous.
It is, therefore, desirable to provide a system and method for at least some of capturing, recovering, retrieving, separating and purifying a variety of inhalation anesthetics such as desflurane and/or sevoflurane from a gas stream that overcomes at least some of the problems with conventional systems. It would be similarly desirable to provide a system and method for at least some of capturing, recovering, separating and purifying halogenated hydrocarbons generally.